CiliaThey beat together and sweep the mucus up toward the throat.
Pseudostratified epitheliumOne layer of cells that looks like several. That is because the nuclei sit at different heights. With cilia it is called pseudostratified ciliated columnar epithelium.
Goblet cellsThey make the mucus.
Basement membraneIt anchors the epithelium to the tissue below.
Lamina propriaThe connective tissue layer of a mucous membrane.
The trachea cut across 5
MucosaThe mucous membrane: epithelium plus lamina propria.
SubmucosaIts glands add mucus and watery fluid.
Hyaline cartilageThe C-rings keep the airway open; they are open at the back.
PerichondriumA layer of dense connective tissue wrapping the cartilage.
Trachealis muscleSmooth muscle; it can narrow the trachea, as in a cough.
How this list was compiled: Every name and detail checked on 2026-09-29 against OpenStax Anatomy and Physiology 2e, sections 4.2 Epithelial Tissue and 4.3 Connective Tissue (pseudostratified ciliated columnar epithelium, goblet cells and mucus, cilia, basement membrane, lamina propria, hyaline cartilage and perichondrium), 22.1 Organs and Structures of the Respiratory System (the trachea's mucosa, C-shaped hyaline cartilage rings open at the back, the trachealis muscle) and 23.1 (mucosa and submucosa), https://openstax.org/books/anatomy-and-physiology-2e/, and against Wikipedia, text only: Mucous membrane, Trachea and Respiratory epithelium. Licence: own work
The drawing: Drawn for this site on 2026-09-29 from plain geometry; nothing traced. Licence: own work
How it works
A mucous membrane lines every tube that opens to the outside. The top drawing enlarges the lining of the airway; the bottom one cuts the trachea across to show where that lining sits among its other layers.
Read the full guide
The lining, then the tube
Numbers 1 to 6 are the lining from the top down: the mucus, the cilia, the tall cells of the epithelium with goblet cells among them, the basement membrane and the lamina propria. Numbers 7 to 11 are the trachea from the inside out: the mucosa, the submucosa, the cartilage with its perichondrium and the muscle at the back.
Mucus traps, cilia sweep: together they move dust up out of the airway.
Questions and answers
What are the parts of a mucous membrane?
An epithelium on top, resting on a basement membrane, with a layer of loose connective tissue called the lamina propria beneath. In the airway the epithelium has cilia and goblet cells that make mucus.
What is pseudostratified epithelium?
A single layer of cells whose nuclei sit at different heights, so it looks like several layers. Every cell touches the basement membrane. In the airway it carries cilia.
Why is the trachea's cartilage C-shaped?
The C-rings hold the airway open, and the open back of each C, closed by the trachealis muscle, lets the esophagus behind it bulge when you swallow.